It is known that traction batteries are provided in electric vehicles in order to make available the electrical energy for driving the electrically driven vehicles. A state of charge display is usually arranged in such vehicles in order to provide the driver with information about the current state of charge of the traction battery. The state of charge display is frequently provided in the region of the instrument panel and indicates the state of charge of the traction battery. The information about the correct state of charge is important for the driver. In this way, with reference to the state of charge, he can assess how large the remaining range of his vehicle is on the basis of the state of charge. He can also draw conclusions about the current driving style or the efficiency with respect to the consumption of energy with this driving style.
It is disadvantageous for the known solutions that during the operation of the vehicle, that is to say during travel, the state of charge of the battery can be determined only in an integrative fashion. The longer this integrative determination lasts and therefore the longer the vehicle is traveling, the greater the extent by which this integrative determination can deviate from the correct state of charge of the traction battery. The correct state of charge of the traction battery can be determined essentially exclusively in the stationary state of the vehicle by the determination of the open-circuit voltage of the traction battery. As soon as a corrected version, and therefore the correct state of charge, has been detected, sliding approximation of the displayed state of charge to the correct state of charge takes place in the known solutions. This is carried out since a displayed step in the displayed state of charge would involve a surprise effect for the driver of the vehicle. This is to be avoided in order to maintain the driver's trust in the displayed state of charge of the state of charge display. However, this leads to a situation in which over a relatively long time of the approximation between the correct state of charge and the displayed state of charge the driver receives at least partially incorrect information about the state of charge of the traction battery.